Cushioning device for rock drills



L. C. BAXLES CUSHIONING DEVICE 'PDR.ROCK DRILLS Sept. 22, 1925.

INVENTOR Lea/1's C-Ba Filed Nuv. 12. 1921 said patents having been assigned to lngeu Patented Sept. 22, 1925.

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LEWIS G. BAYLES, O33 EASTON, PENN$YLVANIA, ASSIGNOR T0 INGERSOLL-RAND,COM-

PANY, OF JERSEYCITY, NEl-V JERSEY, A GORPORAIIUIN NEW JERSEY.

orrsnrourne roaviicn son ROCK DRILLS.

Application filed November 12, 1921. Serial No. 514,849.

To all whom it may concern:

Be it known that I, Lnwrs Barnes, acitizen of the United States, resident of Easton, county of Northampton and State of Pennsylvania, have invented a certain Cushioning Device for Rock Drills, of which the following is a specification, accompanied by drawings.

This invention relates to fluid actuated rock drills of the hammer type, but more particularly to a machine having motive fluid control like thatdisclosed in U. Patent No. 1,268,081, granted to me, June 4, 1918, in which there is a fluid actuated exhaust valve. A. suitable reciprocating exhaust valve for such a machine is disclosed in U. 8. Patent No. 1,278,237, granted September 10, 1918, to Fred M. Slater, both of soll-Rand Co.-

With rock drills of this type, as with other types, the character of the ground is sometimes such that trouble is experienced in extracting the drill steel from the hole, and it is then customary to continue to run the machine while backing out of the hole, so that the vibration and rotation help to extract the drill steel. Butliu such cases, the piston striking the. front end parts of the machine, produces excessive shock and vibration causing breakage.

The primary object of the present inven tion is to create a cushion for the piston in the forward end of the cylinder, in order to prevent the piston "from striking the front head parts and thus preventing the excessive shock and strain throughout the entire machine, whenthe drill steel is moved forward out of the path of thepiston, as in the case when backing out of a tight drill hole.

By closing connnuni'cation between: the auxiliary exhaust port from the front end of the cylinder and the atmosphere, a cushion is formed infront of the piston head, and one suitable and convenient of closing such communication is to provide a manually operated valve locking device by means of which theexhaust valve may be held from reciprocation inone direction, closing the auxiliary exhaust to atmosphere from y "the front end of the cylinder while maintaining the auxiliary exhaust open to at mosphere from therear end of the cylinder.

The piston hammer continues to reciprocate rap dly as a differential valveless hammer,

but the pressure of the expanding air on the larger forwardly acting pressure surface of the. piston head is rapidly dissipated through the open auxiliary exhaust from the rear end of the cylinder, and as there is a strongcushion created in front of the piston head, due to the closing of the auxiliary exhaust to atmosphere at. that end of the cylinder, the blow on the drill steel is light if the shank of the drill steel extends all the way into the cylinder, and the piston does not strike the front head parts. If the drill steel is pulled outwardly, out of the path of the piston, the cushion still has the important function of preventing the piston from striking any of the front head parts.

A machine embodying my invention in one operative form is shown in the accompanying drawings, it being understood that various equivalent devices may be designed for accomplishing my purposes, without departure from the spirit of my invention as disclosed in this specification and defined in the appended claims.

In the drawings, Figure 1 is a side view partly in longitudinal section of a rock drill on the line 11 of Figure 2, looking; in the direction of the arrows,

Figure 2 is a detail horizontal sectional plan view taken through the exhaust valve of Figure 1, with the valve locking device in looking position, and

Figure 3 is a detail sectional view of a portion of Figure 2 showin the valve looking device in withdrawn or unlocked posi net shown as they form no part of the present invention. The back end of the machine is closed by the back head L, having the water connection 0 and the water tube cap P.

The forward piston extension F extends through the front,v cylinder bushing or vis supplied to the machine at the inlet'a controlled by the throttle valve 5 and constant pressure is maintained on the forwardly acting pressure surface 0 of the smaller piston head D. Motive fluid is alternately supplied to and exhausted from the opposite pressure surfaces d and e of the main piston head C, by suitable ports and passages controlled by the piston. Motive fluid is supplied to the front end of the cy-linder through the longitudinal passage A main free exhaust port g is located centrally of the cylinder communicating with the atmosphere at the port 9 for exhaustmg on each side of the piston head C, and a valve controlled auxiliary exhaust is also provided from each end of the cylinder, as indicated by the rear auxiliary exhaust'h and the forward auxiliary exhaust j in the form of ports and passages.

The automatic fluid actuated exhaust valve 7c is preferably located in a valve chest 0 formed transversely in the cylinder A. A valve may be formed in two parts slidably mounted on thebolt 79 on which they reciprocate in normal operation. The bolt is provided with a head q a valve stop 1, a rubber washer s, a valve chest cover t, a lock washer u, and a nut a) for holding the parts together. v I

So far described, the machine does not differ materially from the type of rock drill described in U. S. Patents, 1,268,081, and 1,278,287 hereinbefore referred to; In order, however, to create a cushion in front of the main piston head C under certain conditions which have been described, provide means suitably and conveniently mounted on the valve bolt head for forcing and holding the valve in in'one position as indicated for instance in Figure 2, so

that the valve cannot reciprocate and "at the same time closes communication between the forward auxiliary exhaust passage 7', and atmosphere, while maintaining the rearward auxiliary exhaust passage it open to atmosphere. Under such circumstances, the hammer piston will continue to reciprocate rapidly, performing its functions as a differential valveless piston, but a cushion is formed in front of the main piston head C owing to the closure of the forward auxillary exhaust j to atmosphere and the piston head does not strike the front end parts of the machine. 'Such a condition is shown with the parts in positions indicated in Fig.-

ure 1, it being assumed that the exhaust valve is locked in the position indicated in Figure 2. With the shank of the drill steel all the way in the front head, as indicated in Figure l, a light blow will be struck 'on the drill steel by the hammer piston, due to the fact that the pressure behind the main piston head (.7 will be rapidly dissi pated through the open auxiliary exhaust passage 7L leading from the rearward end of the cylinder, and also due to the-fact that the cushion is formed at the front ofthc piston head. hen the drill steel is withdrawn forwardly in the chuck, out of the path of the piston, the cushion in front of the main piston head continues to prevent injury to the front head parts.

Any suitable and conveniently manipu lated device may be provided for locking the valve in a given position and in this instance, I have chosen to show the locking pin 20 movable longitudinally in a hole formed partly in the head and shank of the valve bolt 72' and partly in an extension y extending from said bolt head 9, so that the head a of the locking pin may be moved against the valve is to force the valve into the position indicated in Figure 2. A transverse pin 2 limits the outward movement of the locking pin and a spring pressed stop 3 is adapted to engage behind the beveled head a of the locking pin to hold the pin in locked position, but permit the pin to be readily withdrawn past the stop 3 to unlocked position as indicatedin- Figure 3. For manipulating the locking pin, a. hollow nut or cap 4 preferably riveted tothe end of the locking pin. as by means of the rivet 5, is adjustable on the bolt head extension 'I/ v as by means of the screw threads 6. Manual rotation of the hollow nut 4 moves the locking pininwardly and outwardly as desired.

I claim:

1. In a fluid actuated rock drill of the hammer type, the combination of a cylinder having a central exhaust port, a piston controlling said exhaust port and adapted to compress motive fluidat either end of said cylinder upon closing said exhaust port, an

auxiliary fluid actuated exhaust valve to relieve such compression, a stop to prevent the operation of said valve for cushioning the frontend of the cylinder andhaving a reduced portion, and means cooperating with only the front end of said cylinder and having a reduced portion, a pin cooperating with said reduced portion for preventing removal of the stop, and automatic means for locking the stop in position.

3. In a fluid actuated rock drill of the hammer type, the combination of a cylinder having a central exhaust port, a piston controlling said exhaust port and adapted to compress motive fluid at either end of said cylinder upon closing said exhaust port, an auxiliary fluid actuated exhaust valve to relieve such compression, a stop to prevent the operation of said valve for cushioning only the front end of said cylinder and having a reduced portion, a pin cooperating With said reduced portion for preventing removal of the stop, a spring pressed plunger for locking the stop in position, and a cap on the stop for manipulating said stop.

4. In a. fluid actuated rock drill of the hammer type, the combination of a cylinder having a central exhaust port, a piston controlling said exhaust port and adapted to bolt, a stop in said extension to lock said valve for cushioning the front end of the cylinder, said stop having a reduced portion, a pin extending transversely through said bolt and cooperating With the reduced portion for preventing removal of the stop, a spring pressed plunger to cooperate with the reduced portion for locking the stop in position, and a cap secured to the stop and cooperating with the extension for manipulating the stop.

In testimony whereof I have signed this specification.

LEWIS C. BAYLES. 

